As well known to those skilled in the art, the circuit breakers currently known can have their operation based on thermal, magnetic, thermomagnetic or electronic principles, and can be used, above all, for the protection of electrical circuits subject to short circuits and/or electrical overloads generated by electric current peaks that exceed a nominal limit previously established, by the movement of electric contacts.
In this sense, it is verified that the circuit breakers function essentially analogously to the electrical switches, that is, they operate in order to change the electrical conduction state of an electric circuit between switched on and switched off. In addition to actuating automatically, the conventional circuit breakers also comprise an operating handle operated by a user. Such operating handles may further be coupled to switching operation mechanisms, which are used primarily in at least two situations: I) in circuit breakers for high current electrical circuits, wherein the force required to move the handle is usually relatively large for manual operations—especially in circuit breakers used in high current circuits, for example in the order of 1600 A; and II) in circuit breakers installed in panel housings which, for safety reasons, tend to be locked, which makes it difficult to directly access the circuit breaker, and wherein it is desirable that the operating handle of the switching operation mechanism is available on the external face thereof.
It is common to note in the prior art that most of these models and constructions of switching operation mechanisms to the circuit breakers are fundamentally based on the functional principle of mechanical cooperation between a pinion and a rack. Such functional principle is widely used in several fields of mechanics and widely known to those skilled in the art.
According to this operating principle, the pinion and the rack, physically coupled together, are usually disposed inside a protective enclosure, coupled to the circuit breaker and are associated with the circuit breaker operating handle. From this, a transmission of movements between these members occur, wherein the rotational movement of the external rotary handle of the switching operation mechanism, exerted manually by a user, triggers the rotational movement of the pinion and, consequently, the displacement of the linear trajectory of the rack, such displacement, which acts directly on the operating handle of the molded case circuit breaker, changing the operating position.
Based on of this context, it is possible to observe that such functional principle comprises some technically disadvantageous aspects.
A relevant technical aspect is that the rack, in its movement, moves in a linear trajectory, whereas the operating handle of the circuit breaker, due to its internal mechanism of action, moves in a rotating trajectory. In this sense, the interaction between these members causes a relative displacement between the rack of the switching operation mechanism and the handle for operating the circuit breaker, consequently, resulting in a high friction and a partial loss of the energy applied in the external rotary handle of said switching operation mechanism.
It should be noted that the cited movement of the handle for operating the molded case circuit breaker is internally rotating, such movement being due to its internal operation mechanism, which performs the opening and closing of its electrical circuit contacts, and observable in a lateral section plane. When the movement of an external rotating handle of the operation mechanism coupled to the molded case circuit breakers is reported, the said rotational movement is observed in the front operating plane.